#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>

using namespace std;

const int N = 2010, M = 10010;

int n, m;
int h[N], w[N], e[N], ne[N], idx;
int dist[N], cnt[N];
bool st[N];
void add(int a, int b, int c)
{
    e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;

}

bool spfa(){
    queue<int > q;
    for(int i = 1; i <= n; i ++)
    {
        st[i] = true;
        q.push(i);
    }
    while(q.size())
    {
        int t =q.front();
        q.pop();
        st[t] = false;
        for(int i = h[t]; i != -1; i = ne[i])
        {
            int j = e[i];
            if(dist[j] > dist[t] + w[i])
            {
                dist[j] = dist[t] + w[i];
                cnt[j] = cnt[t] +1;
                if(cnt[j] >= n) return true;
                if(!st[j])
                {
                    q.push(j);
                    st[j] = true;
                }
            }
        }
    }
    return false ;

}

int main(){

    scanf("%d%d", &n, &m);
    memset(h, -1, sizeof h);
    while(m -- )
    {
        int a, b, c;
        scanf("%d%d%d", &a, &b, &c);
        add(a, b, c);
    }
    if(spfa()) puts("Yes");
    else puts("No");

    return 0;
}